Plasma display panels normally use a binary-coded light-emission-period (discharge period) scheme for displaying digital images with certain gray-scale depth. For a typical 8-bit panel (8-bit system), there are 28.sup.8 =256 possible intensity or gray-scale levels, To translate each data bit into a proper light intensity value on the screen, one TV frame period is divided into 8 subfield periods corresponding to bit 0 through bit 7 of a binary-coded decimal pixel intensity. The number of light-emission pulses (sustain pulses) of each discharge period for a cell in the panel varies from 1, 2, 4, 8, 16, 32, 64 to 128 for subfields 1 to 8 respectively. Although this binary-coded scheme is adequate for displaying still images, annoying false contours (contour artifacts) may appear in the image when either a subject within the image moves, or viewer's eyes move relative to the subject. This phenomenon is termed moving pixel distortion (MPD).
In order to address this problem, some systems employ MPD correction with equalization pulses. In this situation, the transition between subfields that may cause a contour artifact is detected and a light emission pulse is added or subtracted before the transition occurs. To date, these systems have only identified a few transitions for equalization. Furthermore, a sophisticated and costly motion estimator is needed to achieve motion-dependent equalization. Other systems may employ a modified binary-coded light-emission method to scatter the contour artifacts. By increasing the number of subfields from, for example, from 8 to 10 in a 8-bit panel, the method redistributes the length of the two largest light-emission blocks into four blocks with equal length (e.g., 64+128=48+48+48+48). To retain the same total number of pulses as used in the traditional system, the number of sustain pulses included in each of these four newly formed blocks is 48. The contour artifacts that may appear in this modified system are scattered through the image. The result is a more uniform temporal emission achieved by randomly selecting one of the many choices which have the same number of pulses for a given pixel value. When randomization is done at each pixel level, however, the contour artifacts may be transformed into moire-like noise which, in some circumstances, may be a little bit less annoying to the viewer, This form of system only scatters the artifacts, it does not try to minimize them.